With reference to this topic and bug, I have a solution.

https://wpforo.com/community/how-to-and-troubleshooting-2/25971/

After seeing the same problem and being unable to restore wpforo to a new server, I have communicated with Servmask.

This appears to be a wpforo problem, not a all in one wp migration plugin problem. 

Wpforo is changing the original database tables.  They are all stored and imported correctly by AIOWPM.

Wpforo developers please resolve issue. It is imperative that the forums can be backed up and migrated correctly.

The solution:

• On the new server I deleted all the wpforo database tables
• I re-ran the AIOWPM import - all tables then appeared correctly in the db.
• This proves AIOWPM correctly stored and imports the database.
• The forum still wasnt working at this point.
• In Wordpress>wpforo>Tools>Database Tables, errors were indicated
• Ran the repair option here and everything started working OK